Something I have been wondering for awhile...

I have a project I've been messing around with and I would like to implement some of the new features in mysql 4.1.x as opposed to the 4.0.x series.

Now, I have been reading up on mysql/mysqli on the php side of things. One question I havent found the answer to is this:

How can one support both versions? Lets say I want to support mysql 4.0.x and gradually move to 4.1.x and incorporate new functionality. Of course, eventually 4.1.x will be the norm.

Is there a good way to handle this?

This is one of those times where it helps to have a library or object handling the back end, rather than having your apps use the functions directly. That will be a very difficult transition if you have your mysql_* functions strewn across dozens of scripts.

Very true.

I might look into Pear::DB or adodb (not sure offhand if they support both mysql extensions now).

I noticed that phpmyadmin uses a variable to set whether it uses mysql or mysqli.

You can do this.

Basically to use the mysql extensions with a MySQL 4.1 database or better you must set up the user with the OLD_PASSWORD() function and then they will work. When you are ready to use the mysqli functions then just create a new user properly and use that instead.

We do what innova says and in a similar way to phpMyAdmin we have a configuration option to select from mysql or mysqli and you just store the relevant database functions in their own classes.

You can also load the module dynamically if your PHP version has that support enabled. That way, you only use mysqli* when its needed.